As is known in the prior art, many coupling devices have been manufactured and sold for connecting and disconnecting hoses containing pressurized fluid. In particular, it is well-known to have hollow male and female housings coupled together by a pair of pivoted locking arms located on the female housing, wherein the male housing is received by the female housing. The female housing has a pair of side openings which are situated to be opposite a groove in the outside of the male housing when the male housing is inserted into the female housing. A portion of the locking arm located near the pivot passes through the side opening and engages the peripheral groove of the male housing. A gasket forms a seal between the female housing and an end of the male housing.
In an unlocked position, each locking arm is free to swing outward away from and perpendicular to the longitudinal axis of the female housing, such that the portion of the locking arm passing through the side opening no longer engages the peripheral groove of the male housing. In a locked position, each locking arm is parallel to the longitudal axis of the female housing such that the portion of the locking arm passing through the side opening engages the peripheral groove of the male housing.
While this configuration provides a satisfactory coupling mechanism, it suffers from the problem that the pivoted locking arm can be accidentally released. Even if the locking arm is only moved a small amount, the coupling may sufficiently loosen to allow a leak to form.
Consequently, several prior arrangements have been used to maintain the locking arms in a locked position. U.S. Pat. No. 3,124,374 discloses a coupler in which the rotation of the locking arm is prevented from springing outwardly into the unlocked position, as a result of the pressure of the fluid in the pressurized line, by a detent member which is under the bias of a spring so as to retain the locking arm in a locked position. The detent member protrudes from a side of a pair of ears attached to the female housing, near the end of the locking arms. A button, protruding from the top of one ear and the bottom of the other ear, permits the release of the locking arm when the button is pulled backwards such that the detent member no longer holds the locking arm in a locked position.
A problem with this embodiment is that the pair of detent structures are awkwardly arranged such that each locking arm must be unlocked separately by the operator using two hands. In addition, a problem sometimes arises when the coupling is dragged along the ground in that the button is biased backwards such that the detent member is moved out of the path of the locking arm and the locking arm is released. The result is a leak of the liquid from the pressurized line and possible injury to the operator.
In U.S. Pat. No. 3,976,313 each locking arm, when in the locked position, fits between a pair of top and bottom ears that project from the female housing. A spring loaded detent ball projects out of each pair of ears towards the locking arm, so that the locking arm is held in the locked position between the detent balls. Force must be applied to move the lever past these balls in order to release the coupling. A problem with this embodiment is that a relatively small force can pop the cam member free of the detent ball and permit unlocking of the coupling.
In U.S. Pat. No. 4,295,670, each locking arm is held in the locked position by a removable wire pin which engages an ear which passes through a slot in the locking arm. Inserting the pin into a hole in the ear thereby limits the outward movement of the locking arm. A problem with this embodiment and the wire pin is that this embodiment requires the use of two hands to lock the locking arm in the groove engaging position, one to hold the locking arm in the locked position and the other to insert the pin into the opening in the ear. This is compounded by the fact that often times the operator is wearing gloves which must be removed to complete the procedure, and the operator simply cannot be bothered to take off his gloves so the wire pins are not used. In addition, the pins are subject to being lost or sheared which results in the loss of the locking function.